Arrangement for supervising the vacuum, i. e., the gas or vapor pressure, in vacuum discharge apparatus



Feb. 11, 1936. w. DALLENBACH 2,030,781

ARRANGEMENT FOR SUPERVISING THE VACUUM, I E. THE GAS I OR VAPOR PRESSURE, IN VACUUM DISCHARGE APPARATUS Filed July 8, 1935 2 Sheets-Sheet l Feb. 11, 1936. w DALLENBACH 2,030,781

- ARRANGEMENT FOR SUPERVISING THE VACUUM, I E., THE GAS OR ,VAPOR PRESSURE, IN VACUUM DISCHARGE APPARATUS Filed July 8, 1955 2 Sheets-Sheet 2 mMRQW l atented Feb. 11, 1933 PATENT OFFICE ARRANGEMENT FOR SUPERVISING THE VACUUM, I. E., THE GAS OR VAPOR PRES- SURE, IN RATUS VACUUM DISCHARGE APPA-' Walter Dallenbach, Berlin-Gharlottenburg. Germany Application July 8, 1935, Serial No. 30,338 In Germany July 9, 1934 Claims.

My invention relates to an arrangement for supervising the vacuum, i. e., the gas or vapor pressure, in vacuum discharge apparatus.

Arrangements of the kind referred to are known 5 in which an auxiliary discharge is produced between an auxiliary anode and the cathode of the apparatus, and in which a metering electrode is arranged outside the core of the auxiliary discharge. A quantity of charged particles diffuse from the core to the metering electrodein accordance with the vacuum which is to be controlled, thereby infiuencing the control current of an indicating instrument which flows through the metering electrode.

It is also known in such arrangements to provide an obstruction or screen ahead of the auxiliary anode which prevents the formation of a socalled wandering intermediate cathode, by arresting the intermediate cathode in the form of a so-called striction cathode in the reduced cross section of the screen.

It is an object of my invention to provide an arrangement for supervising the vacuum in which certain parts of the old apparatus referred to are used but which is operated upon quite a. different principle.

In the arrangement according to my invention, an auxiliary discharge is also produced between an auxiliary anode and the cathode of the vacuum apparatus to be supervised and a screen is arranged in front of the auxiliary anode. However, in my novel arrangement, an extra metering electrode is not provided but the auxiliary anode which will be referred to as the control anode,

performs the function of the metering electrode. Besides, according to the invention the auxiliary discharge is not operated at constant current intensity, as in the old apparatus referred to, but at intensities in which the chamber partitioned by the screen becomes poor in ions and the intensity of the discharge tends to assume a saturation value, as the potential increases, which is dependent of the vacuum, or gas or vapor pressure, to be supervised. The saturation value is that intensity which can be present in the vacuum apparatus at a given vacuum. The saturation value is metered directly or indirectly by metering means in the circuit of the control 50 anode. In addition to, or instead of the metering device, I may provide switching means which, when the saturation value of the discharge current intensity departs from a predetermined amount, performs certain operations for regulating the vacuum, for instance, throws in a vacuum pump, or means for making up the content of rare gas in the apparatus.

The means which are controlled by the circuit of the control anode, will be referred to as means for regulating the vacuum, although in the case of a metering instrument, the vacuum is not regu lated directly but means are operated manually or mechanically in conformity with the indications of the instrument for regulating the vacuum.

It will now be described how the saturation value of the current intensity is attained, and how it is dependent of the vacuum, or gas or vapor pressure, in the apparatus.

In the striction cathode of the screen, the 1 stream of electrons flows from the cathode to the anode, and the stream of positive ions flows in the opposite direction. For the striction cathode the two streams are at a definite relation to each other, the streams being inversely proportional to the square root from the relation of the mass of electrons (i.e., the quantity of electrons per field unit) to the mass of positive ions. As, from a predetermined current intensity, the chamber between the screen and the control electrode is under a vacuum which is much higher than the vacuum in the apparatus in which the cathode is positioned, the current flowing through the screen is limited by the quantity of neutral gas particles diffusing from the discharge compartment in which the cathode is positioned,into the chamber with the auxiliary or control anode which is partitioned by the screen. This quantity of particles is obviously dependent of the vacuum, i.e., the gas or vapor pressure, ahead of the screen in the direction toward the cathode. From this follows the relation between the vacuum and the saturation value of the current intensity which is utilized according to the invention.

In the accompanying drawings, two arrangements embodying my invention, and a diagram showing the saturation values of the current in-. tensities, are illustrated by way of example.

In the drawings Fig. 1 is an axial section. of a vacuum discharge apparatus in which a metering instrument and a switch for operating vacuum and a gas pump, are in the anode circuit,

Fig. 2 is a diagram of saturation values and Fig. 3 is an axial section of a vacuum discharge apparatus in which a glow discharge tube is arranged in parallel to a choking coil in the anode circuit, for operating means by which the vacuum is regulated.

Referring now to the drawings, and first to mercury rectifier whose vacuum, i. e., whose gas or vapor pressure, is to be supervised. 2 is the mercury cathode of the rectifier, and 3 are the main anodes which are surrounded by anode sleeves d, and inserted by insulators 5. The primary of an alternating-current transformer G is connected to a system, and its secondary is connected to the main anodes 3. In the protection tube "I which is inserted in the vessel I, an auxiliary or control electrode 8 and a screen 9, are inserted, the screen 9 being positioned ahead of the control electrode 8. The circuit 'of the control anode 8 includes asource III ofdirect current by which an auxiliary discharge is maintained between the auxiliary electrode 8 and the main cathode 2.

Fig. 2 shows the current-voltage curve II of the auxiliarydischarge. As the voltage E increases, the intensity I of the discharge current increases also and approaches a saturation value which is about equal to the value Io. This current Io results from the point of intersection between the straight resistance line I8 and the characteristic curve I I and is to be considered as that ourrent-at which the vacuum, or gas .or vapor pressure, in the vessel I has the desired amount. When the pressure in the vessel I increases, i. e., the

, vacuum in the vessel is deteriorated, the current characteristic curve may become such as shown at I2, where the gradient of the curve is shifted toward the higher current amounts Io. Conversely, when the gas orvapor pressure falls in the vessel, i. e., the vacuum is increased, the currentcharacteristic may be such as shown at I3, ascending at the amount of I"o. It follows from the curves illustrated in Fig. 2, that the characteristic curves of current and voltage rise very steeply, so that the current gradually increases with increasing voltage, but tends toward a saturation value. Preferably, that current value is taken as the controlling current for the metering instrument which results from the point of intersection of the current-voltage characteristic curve II with the resistance line I8. 7

Referring now again to Fig'. 1, a metering'instrument M is connected to the anode circuit which may be calibrated so that the vacuum in the vessel I is read directly from the instrument. In addition to, or instead of, the metering instrument I I, an'exciter coil 55 of a switching device may be arranged in the circuit of the control anode 8 and this switching device may control a circuit for cutting in and out an apparatus 22 which may be a vacuum pump, or a pump for supplying rare gas to the apparatus to whose vessel I it is connected by a pipe 23.

Referring now to Fig. 3, the apparatus is arranged as described but' a choking coil I6 and a resistance II are connected in series to the auxiliary or control anode 8. High frequency oscillations then occur between the anode 8 and the screen 8, or through the choking coil l6, as soon as the current through the anode 8 is limited by the screen 9, and no longer by the resistance IT. This is so when the point of intersection with the straight resistance line I8 is on the steeply ascending branch of the characteristic curves I3, II, I2, as shown in Fig. 2.

If the dimensions and current intensities are so determined that such high frequency oscillations occur, a glow-discharge. tube I9, or some other glow-discharge device may be connected in parallel to the choking coil H5, or to the anode 8 and the cathode 9. The device I9 is ionized by Fig. l, the vacuum vessel I may be that of a the high frequency oscillations, and so becomes conductive. A condenser 20 is in series with the glow discharge tube IS. The glow discharge tube,

I9 controls an auxiliary circuit connected to its terminals 2| which in turn controls a device such as 22 in Fig. 1. The device is operated as soon as the. vacuum in the vessel I departs from a prede termined amount.

Obviously, a metering instrument such as the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the oathode at current intensities at which the space in i the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected. to the control anode,

and means in the circuit for regulating the vacuum in .the apparatus.

2. In an arrangement for supervising the vacum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the cathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the cathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and thecurrent intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, and indicating means in the circuit for regulating the vacuum in the apparatus.

3. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effectinga principal discharge between the main anode and the oathode, a control anode, a screen arranged aheadof in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, a switch in the circuit, and means controlled by'the switch, for regulating the vacuum in the apparatus. 7

4. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the cath-' ode, a control anode, a screen arranged'ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary dis! charge between the control anode and the oathode at current intensities at which the space in the chamber of the control anode becomes poorv in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, indicating means in the circuit, a switch, also in the circuit, and means controlled by the switch, for regulating the vacuum in the apparatus.

5. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the oathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode'and the cathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, means for regulating the vacuum in the apparatus, and a switch in the circuit for operating the regulating means when said saturation value departs from a definite amount.

6. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the cathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the cathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, a vacuum pump connected to the apparatus, and a switch in the circuit for controlling the pump.

'7. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the oathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the oathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, a pump for charging the apparatus with rare gas, and a switch in the circuit for controlling the pump.

8. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the oathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for efiecting an auxiliary discharge between the control anode and the oathode at current intensities at which the space in the chamber of the control anode becomes poor 5 in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, means for producing high frequency oscil- 0 lations in the circuit when the normal vacuum in the apparatus is departed from, glow discharge means adapted to be ionized, and to become conductive, under the influence of the high-frequency oscillations, and means controlled by the 15 discharge in the glow discharge means for regulating the vacuum in the apparatus.

9. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the oathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the cathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, means for producing high frequency oscillations in the circuit when the normal vacuum i in the apparatus is departed from, glow discharge means in parallel to the control anode and the cathode, which glow discharge means is adapted to be ionized, and to become conductive, under the influence of the high-frequency oscillations, and means controlled by the discharge in the glow discharge means for regulating the vacuum in the apparatus.

10. In an arrangement for supervising the vacuum in vacuum discharge apparatus, a main anode, a cathode, means for effecting a principal discharge between the main anode and the oathode, a control anode, a screen arranged ahead of the control anode and partitioning the chamber of the control anode from the interior of the apparatus, means for effecting an auxiliary discharge between the control anode and the cathode at current intensities at which the space in the chamber of the control anode becomes poor in ions, and the current intensity in the auxiliary discharge tends to assume a saturation value which is a function of the vacuum in the apparatus, a circuit connected to the control anode, means for producing high frequency oscillations in the circuit when the normal vacuum in the apparatus is departed from, a choking coil in the circuit of the control anode, glow discharge means in parallel to the coil, which glow discharge means is adapted to be ionized, and to become conductive, under the influence of the high frequency oscillations, and means controlled by the discharge in the glow discharge means for regulating the vacuum in the apparatus.

WALTER DALLENBACH. 

